1. Field of the Invention
This invention relates to a tuning apparatus and a method of producing the same and more particularly it relates to improvements in the construction of the tuning capacitor and terminals.
2. Description of the Prior Art
FIG. 1 is a sectional view of a construction for explanation of a prior art tuning apparatus of interest to the present invention, illustrating a conventional intermediate frequency transformer. The intermediate frequency transformer 10 shown therein comprises a resin base 12 having a recess 11 formed in the bottom thereof, with coils 13 mounted on the base 12. In association with said coils 13, there are provided a drum core 14 and a cap core 15, which is threadedly installed, adjustments of the inductance being made by tuning said cap core 15. Received in the recess 11 formed in the base 12 is a tuning capacitor 16 of, e.g. the lead-attached cylinder type. A plurality of round-pin terminals 17 are pressure-inserted into the surface of the base 12. Leads 18 from said coils 13 and leads 19 from said capacitor 16 are wound around said pin terminals 17 and fixed in position by the solder dip process.
The conventional intermediate frequency transformer as described above, however, has disadvantages or problems which follow.
When the pressure-inserting operation on the terminals 17 is to be carried out by an automatic machine, the cost will increase unless the number of articles to be produced is relatively large. Since the tuning capacitor 16 employed is, in most cases, of the lead-attached cylinder type, it is difficult to automate the installing operation and the size is large. Since the tuning capacitor 16 is received in the recess 11 formed in the bottom surface of the base 12, the characteristics would be deteriorated as by the sticking of flux during the soldering operation. Since the tuning capacitor 16 itself is exposed, it is susceptible to moisture and other influences from the ambient atmosphere. Further, since the terminals 17 are pressure-inserted after the formation of the base 12, they tend to come off, breaking the leads.